Corona generator

Abstract

A corona generator method and apparatus preferably for generating ozone, employing a plurality of corona generating cells each comprising a pair of parallel spaced-apart electrodes having a fired-on coating of porcelain enamel. The electrodes are connected to an AC voltage source of sufficient voltage to generate a corona discharge, and an oxygen-containing gas is passed between the electrodes to generate ozone. A high concentration ozone is produced as well as a large quantity of ozone, without water cooling, and at voltages of approximately 6,000 volts. An equation setting forth, for the first time, the interrelationships between the various parameters in a corona generator is derived by Applicant. According to the invention, the corona power is maximized by maximizing the expression ε/Td, where epsilon is the dielectric constant of the porcelain enamel coating and Td is the dielectric thickness.

I claim: 
     
       1. In a corona generator including a pair of spaced-apart, adjacent electrodes defining a corona discharge chamber between facing interior surfaces of said electrodes, the improvement wherein at least one of said electrodes has a metal electrode substrate having a thin, hard, fired-on coating of porcelain enamel having a thickness of less than 20 mils and being fired onto an interior surface thereof at a temperature sufficiently high to bond said porcelain enamel coating onto said surface of said electrode. 
     
     
       2. The corona generator according to claim 1 wherein said coating comprises a plurality of separately fired-on individual layers of porcelain enamel. 
     
     
       3. The apparatus according to claim 2 wherein said coating is fired-on at a temperature of about 1500° F. 
     
     
       4. The apparatus according to claim 3 wherein said coating has a dielectric constant of at least 5. 
     
     
       5. The apparatus according to claim 4 wherein said substrate and said coating each have a constant thickness and wherein said coating has a flat, smooth surface. 
     
     
       6. The apparatus according to claim 5 wherein said substrate is flat over a major portion of its area. 
     
     
       7. The apparatus according to claim 6 wherein said surface of said substrate is etched prior to said coating being fired thereon. 
     
     
       8. The apparatus according to claim 7 wherein said porcelain enamel has a high softening point temperature at least equal to that of glass. 
     
     
       9. The apparatus according to claim 8 wherein the total dielectric thickness Td in mils of said coating, and the dielectric constant ε of said p.e. are such that the value of the expression ε/Td is greater than 0.1. 
     
     
       10. The apparatus according to claim 9 wherein said coating is uniform and is free of voids. 
     
     
       11. The apparatus according to claim 10 wherein said coating is free of conductive particles. 
     
     
       12. The apparatus according to claim 1 wherein said coating has a dielectric constant of at least 5. 
     
     
       13. The apparatus according to claim 1 wherein said substrate and said coating each have a constant thickness and wherein said coating has a flat, smooth surface. 
     
     
       14. The apparatus according to claim 1 wherein said substrate is flat over a major portion of its area. 
     
     
       15. The apparatus according to claim 1 wherein said coating is fired-on at a temperature of about 1500° F. 
     
     
       16. The apparatus according to claim 1 wherein said surface of said substrate is etched prior to said coating being fired thereon. 
     
     
       17. The apparatus according to claim 1 wherein said coating is uniform and is free of voids. 
     
     
       18. The apparatus according to claim 1 wherein said coating is free of conductive particles. 
     
     
       19. The apparatus according to claim 1 wherein said porcelain enamel has a high softening point temperature at least equal to that of glass. 
     
     
       20. The apparatus according to claim 1 wherein the total dielectric thickness Td in mils of said coating, and the dielectric constant ε of said p.e. are such that the value of the expression ε/Td is greater than 0.1. 
     
     
       21. The apparatus according to claim 1 wherein said at least one electrode comprises both of said electrodes. 
     
     
       22. The apparatus according to claim 21 wherein said coatings comprise a plurality of separately fired-on individual porcelain enamel layers, and said electrodes are made of etched, decarbonized steel, on which said coatings are fired at about 1500° F.